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Whereas most dragons in European mythology are linked to the elements of fire and destruction, dragons in Korean mythology are primarily benevolent beings related to water and agriculture, often considered bringers of rain and clouds. Hence, many Korean dragons are said to have resided in rivers, lakes, oceans, or even deep mountain ponds.

The symbol of the dragon has been used extensively, both in Korean mythology and ancient Korean art.

Ancient texts sometimes mention sentient speaking dragons, capable of understanding such complex emotions such as devotion, kindness, and gratitude. One particular Korean legend speaks of the great King Munmu, who on his deathbed wished to become a "Dragon of the East Sea in order to protect Korea".

The Korean dragon is in many ways very similar in appearance to dragons of Chinese, Vietnamese and Japanese mythology. It differs from the Chinese dragon in that it developed a longer beard.

Very occasionally a dragon may be depicted as carrying an orb known as the Yeouiju (여의주), the Korean name for the mythical Cintamani, in its claws or in its mouth. It was said that whoever could wield the Yeouiju was blessed with the abilities of omnipotence and creation at will, and that only four-toed dragons (who had thumbs with which to hold the orbs) were both wise and powerful enough to wield these orbs, as opposed to the lesser, three-toed dragons.

As with China, the number nine is significant and auspicious in Korea, and dragons were said to have 81 (9×9) scales on their backs, representing yang essence.

Korean folk mythology states that most dragons were originally Imugis (이무기), or lesser dragons, which were said to resemble gigantic serpents. There are a few different versions of Korean folklore that describe what imugis are and how they aspire to become full-fledged dragons. Koreans thought that an Imugi could become a true dragon, or yong or mireu, if it caught a Yeouiju which had fallen from heaven. Another explanation states they are hornless creatures resembling dragons who have been cursed and thus were unable to become dragons. By other accounts,[according to whom?] an Imugi is a proto-dragon which must survive one thousand years in order to become a fully fledged dragon. In either case they are said to be large, benevolent, python-like creatures that live in water or caves, and their sighting is associated with good luck.

In the 2007 South Korean film D-War, two Imugi, of which one was benevolent and the other evil, were seen competing for possession of a source of power (the Yeouiju) by which one of them could become a dragon. Ultimately, the evil Imugi is destroyed by his rival moments after the latter had captured the source. Here, the two are shown to be physically different, in that the evil Imugi is darker-colored, more slender, and distinguished by an inflexible hood similar to that of a cobra, whereas the good Imugi is paler, stockier, hoodless; and more closely resembles a python. Narration in the film implies that many Imugi exist at a time, whereof one is designated to become a dragon.

The Alosha series by Christopher Pike features a variation of the Imugi called a "koul". A koul is a snakelike, gigantic proto-dragon that must pass three tests of courage; Coming to aid of others, the act of swimming, and a literal 'leap' of faith in order to become a dragon. Upon coming to the aid of others, the koul grows legs; after swimming through water, the koul is able to breathe fire; upon making the leap of faith, the koul immediately sprouts wings. A successful koul resembles a European dragon, whereas a koul who has completed only one or two of its tests resembles a Chinese dragon or Korean dragon of the type described above.

The Korean cockatrice is known as a gye-lyong (계룡/鷄龍), which literally means chicken-dragon; they do not appear as often as dragons. They are sometimes seen as chariot-pulling beasts for important legendary figures or for the parents of legendary heroes. One such legend involves the founding of the Kingdom of Silla, whose princess was said to have been born from a cockatrice egg. It is also the origin of the name for the city of Gyeryong in South Chungcheong province.